Bicycle rear sprocket assembly and bicycle rear sprocket

ABSTRACT

A bicycle rear sprocket comprises a sprocket support member, a first attachment portion, and a second attachment portion. The sprocket support member comprises a first support member and a second support member. The first support member includes a first radially outer portion and a first radially inner portion. The second support member includes a second radially outer portion and a second radially inner portion. The first support member faces the second support member in the axial direction to define an axial gap provided between the first support member and the second support member in the axial direction. The first radially outer portion of the first support member is configured to be attached to the second radially outer portion of the second support member via a bicycle sprocket positioned between the first attachment portion and the second attachment portion in the axial direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of the U.S. patentapplication Ser. No. 14/838,427 filed Aug. 28, 2015. The contents ofthis application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a bicycle rear sprocket assembly and abicycle rear sprocket.

Discussion of the Background

Bicycling is becoming an increasingly more popular form of recreation aswell as a means of transportation. Moreover, bicycling has become a verypopular competitive sport for both amateurs and professionals. Whetherthe bicycle is used for recreation, transportation or competition, thebicycle industry is constantly improving the various components of thebicycle. One bicycle component that has been extensively redesigned is abicycle sprocket.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, a bicycle rearsprocket comprises a sprocket support member, a first attachmentportion, and a second attachment portion. The sprocket support member isrotatable about a rotational center axis. The sprocket support memberhas a first axial side and a second axial side opposite to the firstaxial side in an axial direction parallel to the rotational center axis.The sprocket support member comprises a first support member and asecond support member. The first support member includes a firstradially outer portion and a first radially inner portion. The firstsupport member at least partly constitutes the first axial side. Thesecond support member includes a second radially outer portion and asecond radially inner portion. The second support member at least partlyconstitutes the second axial side. The first support member faces thesecond support member in the axial direction to define an axial gapprovided between the first support member and the second support memberin the axial direction. The first attachment portion is provided at thefirst radially outer portion of the first support member. The secondattachment portion is provided at the second radially outer portion ofthe second support member. The first radially outer portion of the firstsupport member is configured to be attached to the second radially outerportion of the second support member via a bicycle sprocket positionedbetween the first attachment portion and the second attachment portionin the axial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1 is a side elevational view of a bicycle rear sprocket assembly inaccordance with a first embodiment.

FIG. 2 is a partial cross-sectional view of the bicycle rear sprocketassembly taken along line II-II of FIG. 1.

FIG. 3 is a perspective view of a sprocket support member of the bicyclerear sprocket assembly.

FIG. 4 is a partial perspective cross-sectional view of the sprocketsupport member.

FIG. 5 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a second embodiment.

FIG. 6 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a third embodiment.

FIG. 7 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a fourth embodiment.

FIG. 8 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a fifth embodiment.

FIG. 9 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a sixth embodiment.

FIG. 10 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a seventh embodiment.

FIG. 11 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with an eighth embodiment.

FIG. 12 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a ninth embodiment.

FIG. 13 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with a tenth embodiment.

FIG. 14 is a partial cross-sectional view of a bicycle rear sprocketassembly in accordance with an eleventh embodiment.

FIG. 15 is a side elevational view of a bicycle rear sprocket assemblyin accordance with a twelfth embodiment.

FIG. 16 is a side elevational view of a bicycle rear sprocket assemblyin accordance with a thirteenth embodiment.

FIG. 17 is a partial cross-sectional view of the bicycle rear sprocketassembly taken along line XVII-XVII of FIG. 16.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

First Embodiment

Referring initially to FIG. 1, a bicycle rear sprocket assembly 10 inaccordance with a first embodiment is configured to be engaged with abicycle chain C. The bicycle rear sprocket assembly 10 is configured tobe rotated about a rotational center axis A1 in a driving rotationaldirection D11 during pedaling. The driving rotational direction D11 isdefined along a circumferential direction D1 of the bicycle rearsprocket assembly 10.

In the present application, the following directional terms “front”,“rear”, “forward”, “rearward”, “left”, “right”, “transverse”, “upward”and “downward” as well as any other similar directional terms refer tothose directions which are determined on the basis of a user (e.g., arider) who sits on a saddle (not shown) of a bicycle with facing ahandlebar (not shown). Accordingly, these terms, as utilized to describethe bicycle rear sprocket assembly 10, should be interpreted relative tothe bicycle equipped with the bicycle rear sprocket assembly 10 as usedin an upright riding position on a horizontal surface.

As seen in FIG. 1, the bicycle rear sprocket assembly 10 comprises asprocket support member 12. The sprocket support member 12 is rotatableabout the rotational center axis A1. The bicycle rear sprocket assembly10 may further comprise a first sprocket 14 and a second sprocket 16.

The first sprocket 14 comprises a first sprocket body 18 and a pluralityof first sprocket teeth 20. The first sprocket body 18 is rotatableabout the rotational center axis A1. The first sprocket body 18 has anannular shape. The plurality of first sprocket teeth 20 protrude from anouter periphery of the first sprocket body 18. The plurality of firstsprocket teeth 20 are configured to be engaged with the bicycle chain C.

The second sprocket 16 comprises a second sprocket body 22 and aplurality of second sprocket teeth 24. The second sprocket body 22 isrotatable about the rotational center axis A1. The second sprocket body22 has an annular shape. The plurality of second sprocket teeth 24protrude from an outer periphery of the second sprocket body 22. Theplurality of second sprocket teeth 24 are configured to be engaged withthe bicycle chain C.

A total number of the plurality of first sprocket teeth 20 is differentfrom a total number of the plurality of second sprocket teeth 24. Inthis embodiment, the total number of the plurality of first sprocketteeth 20 is larger than the total number of the plurality of secondsprocket teeth 24. However, the total number of the plurality of firstsprocket teeth 20 can be smaller than the total number of the pluralityof second sprocket teeth 24.

As seen in FIG. 2, the sprocket support member 12 comprises a firstsupport member 26 and a second support member 28. The first supportmember 26 includes a first radially outer portion 30 and a firstradially inner portion 32. The first radially outer portion 30 isprovided radially outward of the first radially inner portion 32. Thesecond support member 28 includes a second radially outer portion 34 anda second radially inner portion 36. The second radially outer portion 34is provided radially outward of the second radially inner portion 36.

The first radially outer portion 30 is provided at an axial positionsubstantially equal to an axial position of the first radially innerportion 32 in the illustrated embodiment. In contrast, the secondradially outer portion 34 is offset from the second radially innerportion 36 in an axial direction D2 parallel to the rotational centeraxis A1 in the illustrated embodiment. In this embodiment, an axialdistance defined between the first radially inner portion 32 and thesecond radially inner portion 36 in the axial direction D2 is longerthan an axial distance defined between the first radially outer portion30 and the second radially outer portion 34 in the axial direction D2.The first radially outer portion 30 may be offset from the firstradially inner portion 32 in an axial direction D2 parallel to therotational center axis A1 whereas the second radially outer portion 34may be provided at an axial position substantially equal to an axialposition of the second radially inner portion 36. Further, both of thefirst radially outer portion 30 and the second radially outer portion 34may be offset from the first radially inner portion 32 and the secondradially inner portion 36 respectively in an axial direction D2 parallelto the rotational center axis A1.

The first radially outer portion 30 of the first support member 26 isconfigured to be attached to the second radially outer portion 34 of thesecond support member 28. The first support member 26 includes one of ametallic material and a non-metallic material. The second support member28 includes one of a metallic material and a non-metallic material. Inthis embodiment, the first support member 26 includes the metallicmaterial. The second support member 28 includes the metallic material.Examples of the metallic material include iron, stainless steel,titanium, and aluminum. The first radially outer portion 30 isconfigured to be attached to the second radially outer portion 34 viaone of adhesive, diffusion bonding, and caulking. In this embodiment,the first radially outer portion 30 is configured to be attached to thesecond radially outer portion 34 via diffusion bonding. The firstradially outer portion 30 is in contact with the second radially outerportion 34.

As seen in FIG. 2, the sprocket support member 12 has a first axial sideS1 and a second axial side S2 opposite to the first axial side S1 in theaxial direction D2 parallel to the rotational center axis A1. The firstsupport member 26 at least partly constitutes the first axial side S1.The second support member 28 at least partly constitutes the secondaxial side S2. In this embodiment, the first support member 26 entirelyconstitutes the first axial side S1. The second support member 28entirely constitutes the second axial side S2. However, the firstsupport member 26 can partly constitute the first axial side S1. Thesecond support member 28 can partly constitute the second axial side S2.

The first support member 26 faces the second support member 28 in theaxial direction D2 to define an axial gap G provided between the firstsupport member 26 and the second support member 28 in the axialdirection D2.

As seen in FIG. 3, the first support member 26 includes a plurality offirst arms 38 extending between the first radially outer portion 30 andthe first radially inner portion 32. The first arms 38 are arranged inthe circumferential direction D1 relative to the rotational center axisA1 and are spaced apart from each other in the circumferential directionD1. In this embodiment, the first radially outer portion 30 includesfirst radially outer parts 40. The first arms 38 respectively extendbetween the first radially outer parts 40 and the first radially innerportion 32.

As seen in FIG. 3, the second support member 28 includes a plurality ofsecond arms 42 extending between the second radially outer portion 34and the second radially inner portion 36. The second arms 42 arearranged in the circumferential direction D1 relative to the rotationalcenter axis A1 and are spaced apart from each other in thecircumferential direction D1. In this embodiment, the second radiallyouter portion 34 includes second radially outer parts 44. The secondarms 42 respectively extends between the second radially outer parts 44and the second radially inner portion 36.

As seen in FIG. 3, at least one of the first arms 38 includes a firstopening 46 provided between the first radially outer portion 30 and thefirst radially inner portion 32. In this embodiment, each of the firstarms 38 includes the first opening 46 provided between the firstradially outer portion 30 and the first radially inner portion 32.

At least one of the second arms 42 includes a second opening 48 providedbetween the second radially outer portion 34 and the second radiallyinner portion 36. In this embodiment, each of the second arms 42includes the second opening 48 provided between the second radiallyouter portion 34 and the second radially inner portion 36.

As seen in FIG. 2, the first arms 38 respectively face the second arms42 in the axial direction D2 to define the axial gap G. The firstopenings 46 respectively face the second openings 48 in the axialdirection D2 in the illustrated embodiment. The first openings 46 mayrespectively be offset from the second openings 48. The first opening 46and the second opening 48 are in communication with the axial gap G.

The first support member 26 has a first thickness T11. The secondsupport member 28 has a second thickness T12. In this embodiment, thesecond thickness T12 is substantially equal to the first thickness T11.In this embodiment, the first arms 38 have the first thickness T11. Thesecond arms 42 have the second thickness T12.

As seen in FIG. 2, the bicycle rear sprocket assembly 10 comprises afirst sprocket attachment portion 50 and a second sprocket attachmentportion 52. The first sprocket 14 is configured to be attached to thefirst sprocket attachment portion 50. The second sprocket 16 isconfigured to be attached to the second sprocket attachment portion 52.The first sprocket attachment portion 50 is provided at the first axialside S1. The second sprocket attachment portion 52 is provided at thesecond axial side S2.

In this embodiment, as seen in FIG. 4, the first sprocket attachmentportion 50 includes first attachment surfaces 54 arranged in thecircumferential direction D1. The first attachment surfaces 54 arespaced apart from each other in the circumferential direction D1. Thefirst attachment surfaces 54 are respectively provided at the firstradially outer parts 40. As seen in FIG. 2, the first attachmentsurfaces 54 are provided on the first axial side S1. The firstattachment surfaces 54 are in contact with the first sprocket 14 in astate where the first sprocket 14 is attached to the first sprocketattachment portion 50.

Similarly, as seen in FIG. 3, the second sprocket attachment portion 52includes second attachment surfaces 56 arranged in the circumferentialdirection D1. The second attachment surfaces 56 are spaced apart fromeach other in the circumferential direction D1. The second attachmentsurfaces 56 are respectively provided at the second radially outer parts44. As seen in FIG. 2, the second attachment surfaces 56 are provided onthe second axial side S2. The second attachment surfaces 56 are incontact with the second sprocket 16 in a state where the second sprocket16 is attached to the second sprocket attachment portion 52.

As seen in FIG. 2, the first sprocket 14 is configured to be attached tothe first sprocket attachment portion 50 via one of caulking, adhesive,integral molding, and diffusion bonding. In this embodiment, the firstsprocket 14 is configured to be attached to the first sprocketattachment portion 50 via caulking. In a case where the first sprocket14 is attached to the first sprocket attachment portion 50 via caulking,the first sprocket 14 is fixedly engaged with the first sprocketattachment portion 50 by deforming at least one of the first sprocket14, the first sprocket attachment portion 50, and other parts when thebicycle rear sprocket assembly 10 is manufactured. Specifically, thefirst sprocket 14 is attached to the first sprocket attachment portion50 via rivets 58.

The second sprocket 16 is configured to be attached to the secondsprocket attachment portion 52 via one of caulking, adhesive, integralmolding, and diffusion bonding. In this embodiment, the second sprocket16 is configured to be attached to the second sprocket attachmentportion 52 via caulking. In a case where the second sprocket 16 isattached to the second sprocket attachment portion 52 via caulking, thesecond sprocket 16 is fixedly engaged with the second sprocketattachment portion 52 by deforming at least one of the second sprocket16, the second sprocket attachment portion 52, and other parts when thebicycle rear sprocket assembly 10 is manufactured. Specifically, thesecond sprocket 16 is attached to the second sprocket attachment portion52 via the rivets 58.

Each of the first radially outer parts 40 includes a first attachmenthole 60. Each of the second radially outer parts 44 includes a secondattachment hole 62. The rivet 58 extends through the first attachmenthole 60 and the second attachment hole 62.

As seen in FIGS. 2 and 4, the bicycle rear sprocket assembly 10 furthercomprises a hub engagement portion 64 with which a bicycle hub assembly2 is to be engaged. The hub engagement portion 64 is provided integrallywith at least one of the first radially inner portion 32 of the firstsupport member 26 and the second radially inner portion 36 of the secondsupport member 28 as a single unitary member. The hub engagement portion64 is a separate member from at least one of the first radially innerportion 32 of the first support member 26 and the second radially innerportion 36 of the second support member 28.

In this embodiment, the hub engagement portion 64 is provided integrallywith the second radially inner portion 36 of the second support member28 as a single unitary member e.g. by burring, cutting, casting and soon. The hub engagement portion 64 is a separate member from the firstradially inner portion 32 of the first support member 26. The hubengagement portion 64 includes one of a metallic material and anon-metallic material. In this embodiment, the hub engagement portion 64includes the metallic material. However, the hub engagement portion 64can include a resin material. Examples of the metallic material includeiron, stainless steel, titanium, and aluminum.

As seen in FIGS. 2 and 4, the first radially inner portion 32 isconfigured to be attached to the second radially inner portion 36 viathe hub engagement portion 64. The hub engagement portion 64 is providedbetween the first radially inner portion 32 and the second radiallyinner portion 36. The hub engagement portion 64 is configured to beattached to the first radially inner portion 32 of the first supportmember 26 via one of caulking, adhesive, integral molding, and diffusionbonding. In this embodiment, the hub engagement portion 64 is configuredto be attached to the first radially inner portion 32 of the firstsupport member 26 via diffusion bonding. The hub engagement portion 64is in contact with the first radially inner portion 32.

In this embodiment, as seen in FIGS. 2 and 4, each of the first radiallyinner portion 32 and the second radially inner portion 36 includes asplined part having a shape substantially identical to a shape of asplined part of the hub engagement portion 64. However, at least one ofthe first radially inner portion 32 and the second radially innerportion 36 can have a shape different from the shape of the hubengagement portion 64.

With the bicycle rear sprocket assembly 10, the first support member 26faces the second support member 28 in the axial direction D2 to definethe axial gap G provided between the first support member 26 and thesecond support member 28 in the axial direction D2. Accordingly, it ispossible to save weight of the bicycle rear sprocket assembly 10 withmaintaining the desired strength of the bicycle rear sprocket assembly10.

Second Embodiment

A bicycle rear sprocket assembly 210 in accordance with a secondembodiment will be described below referring to FIG. 5. The bicycle rearsprocket assembly 210 has the same configuration as the bicycle rearsprocket assembly 10 except for the second support member 28. Elementshaving substantially the same function as those in the first embodimentwill be numbered the same here, and will not be described again indetail here for the sake of brevity.

As seen in FIG. 5, in the bicycle rear sprocket assembly 210, the secondsupport member 28 has a second thickness T22 different from the firstthickness T11. In this embodiment, the second thickness T22 is largerthan the first thickness T11. However, the second thickness T22 can besmaller than the first thickness T11.

With the bicycle rear sprocket assembly 210, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Third Embodiment

A bicycle rear sprocket assembly 310 in accordance with a thirdembodiment will be described below referring to FIG. 6. The bicycle rearsprocket assembly 310 has the same configuration as the bicycle rearsprocket assembly 10 except for the hub engagement portion 64. Elementshaving substantially the same function as those in the above embodimentswill be numbered the same here, and will not be described again indetail here for the sake of brevity.

As seen in FIG. 6, in the bicycle rear sprocket assembly 310, the hubengagement portion 64 is provided integrally with the first radiallyinner portion 32 of the first support member 26 as a single unitarymember e.g. by burring, cutting, casting and so on. The hub engagementportion 64 is a separate member from the second radially inner portion36 of the second support member 28. The hub engagement portion 64 isconfigured to be attached to the second radially inner portion 36 viaone of adhesive, diffusion bonding, and caulking. In this embodiment,the hub engagement portion 64 is configured to be attached to the secondradially inner portion 36 via diffusion bonding.

With the bicycle rear sprocket assembly 310, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Fourth Embodiment

A bicycle rear sprocket assembly 410 in accordance with a fourthembodiment will be described below referring to FIG. 7. The bicycle rearsprocket assembly 410 has the same configuration as the bicycle rearsprocket assembly 10 except for the hub engagement portion 64. Elementshaving substantially the same function as those in the above embodimentswill be numbered the same here, and will not be described again indetail here for the sake of brevity.

As seen in FIG. 7, in the bicycle rear sprocket assembly 410, the hubengagement portion 64 is provided integrally with the first radiallyinner portion 32 and the second radially inner portion 36 as a singleunitary member. Each of the first support member 26, the second supportmember 28, and the hub engagement portion 64 includes one of a metallicmaterial and a non-metallic material. For example, each of the firstsupport member 26, the second support member 28, and the hub engagementportion 64 includes the non-metallic material. Each of the first supportmember 26, the second support member 28, and the hub engagement portion64 includes a resin material. The first support member 26, the secondsupport member 28, and the hub engagement portion 64 are integrallyformed via integral molding, for example. Each of the first supportmember 26, the second support member 28, and the hub engagement portion64 can include the metallic material.

With the bicycle rear sprocket assembly 410, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Fifth Embodiment

A bicycle rear sprocket assembly 510 in accordance with a fifthembodiment will be described below referring to FIG. 8. The bicycle rearsprocket assembly 510 has the same configuration as the bicycle rearsprocket assembly 10 except for the hub engagement portion 64. Elementshaving substantially the same function as those in the above embodimentswill be numbered the same here, and will not be described again indetail here for the sake of brevity.

As seen in FIG. 8, in the bicycle rear sprocket assembly 510, the hubengagement portion 64 is a separate member from the first radially innerportion 32 of the first support member 26 and the second radially innerportion 36 of the second support member 28. The first radially innerportion 32 is configured to be attached to the second radially innerportion 36 via the hub engagement portion 64. The hub engagement portion64 is configured to be attached to the first radially inner portion 32and the second radially inner portion 36 via one of caulking, adhesive,integral molding, and diffusion bonding. In this embodiment, the hubengagement portion 64 is configured to be attached to the first radiallyinner portion 32 and the second radially inner portion 36 via diffusionbonding.

With the bicycle rear sprocket assembly 510, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Sixth Embodiment

A bicycle rear sprocket assembly 610 in accordance with a sixthembodiment will be described below referring to FIG. 9. The bicycle rearsprocket assembly 610 has the same configuration as the bicycle rearsprocket assembly 10 except for the hub engagement portion 64. Elementshaving substantially the same function as those in the above embodimentswill be numbered the same here, and will not be described again indetail here for the sake of brevity.

As seen in FIG. 9, in the bicycle rear sprocket assembly 610, the hubengagement portion 64 includes a first hub engagement portion 643 and asecond hub engagement portion 645. The first hub engagement portion 643is a separate member from the second hub engagement portion 645 and isprovided integrally with the first radially inner portion 32 of thefirst support member 26 as a single unitary member e.g. by burring,cutting, casting and so on. The second hub engagement portion 645 is aseparate member from the first hub engagement portion 643 and isprovided integrally with the second radially inner portion 36 of thesecond support member 28 as a single unitary member e.g. by burring,cutting, casting and so on.

The first hub engagement portion 643 includes one of a metallic materialand a non-metallic material. The second hub engagement portion 645includes one of a metallic material and a non-metallic material. In thisembodiment, each of the first hub engagement portion 643 and the secondhub engagement portion 645 includes the metallic material. The first hubengagement portion 643 is configured to be attached to the second hubengagement portion 645 via one of caulking, adhesive, integral molding,and diffusion bonding. In this embodiment, the first hub engagementportion 643 is configured to be attached to the second hub engagementportion 645 via diffusion bonding.

With the bicycle rear sprocket assembly 610, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Seventh Embodiment

A bicycle rear sprocket assembly 710 in accordance with a seventhembodiment will be described below referring to FIG. 10. The bicyclerear sprocket assembly 710 has the same configuration as the bicyclerear sprocket assembly 10 except for the first support member 26, thesecond support member 28, and the hub engagement portion 64. Elementshaving substantially the same function as those in the above embodimentswill be numbered the same here, and will not be described again indetail here for the sake of brevity.

As seen in FIG. 10, in the bicycle rear sprocket assembly 710, the firstsupport member 26 includes a first radially inner portion 732. Thesecond support member 28 includes a second radially inner portion 736.The first radially inner portion 732 is configured to be directlyattached to the second radially inner portion 736. In this embodiment,the first radially inner portion 732 extends in the axial direction D2toward the second radially inner portion 736. The second radially innerportion 736 extends in the axial direction D2 toward the first radiallyinner portion 732. An axial end of the first radially inner portion 732is attached to an axial end of the second radially inner portion 736.

The first radially inner portion 732 is configured to be attached to thesecond radially inner portion 736 via one of adhesive, diffusionbonding, and caulking. In this embodiment, the first radially innerportion 732 is configured to be attached to the second radially innerportion 736 via adhesive.

The bicycle rear sprocket assembly 710 comprises a hub engagementportion 764 with which the bicycle hub assembly 2 is to be engaged. Thehub engagement portion 764 has substantially the same structure as thatof the hub engagement portion 64 in the first embodiment. However, thehub engagement portion 764 is a separate member from the first radiallyinner portion 732 of the first support member 26 and the second radiallyinner portion 736 of the second support member 28. The hub engagementportion 764 is configured to be attached to the first radially innerportion 732 and the second radially inner portion 736. The hubengagement portion 764 is configured to be attached to the firstradially inner portion 732 and the second radially inner portion 736 viaone of adhesive, diffusion bonding, and caulking. In this embodiment,the hub engagement portion 764 is configured to be attached to the firstradially inner portion 732 and the second radially inner portion 736 viaadhesive. The hub engagement portion 764 is provided radially inward ofthe first radially inner portion 732 and the second radially innerportion 736.

With the bicycle rear sprocket assembly 710, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Eighth Embodiment

A bicycle rear sprocket assembly 810 in accordance with an eighthembodiment will be described below referring to FIG. 11. The bicyclerear sprocket assembly 810 has the same configuration as the bicyclerear sprocket assembly 10 except for the first support member 26 and thesecond support member 28. Elements having substantially the samefunction as those in the above embodiments will be numbered the samehere, and will not be described again in detail here for the sake ofbrevity.

As seen in FIG. 11, in the bicycle rear sprocket assembly 810, the firstradially outer portion 30 of the first support member 26 is providedintegrally with the second radially outer portion 34 of the secondsupport member 28 as a single unitary member. Specifically, the firstradially outer parts 40 are respectively provided integrally with thesecond radially outer parts 44 as a single unitary member. For example,the first support member 26 and the second support member 28 include anon-metallic material such as a resin material. The first support member26 and the second support member 28 are formed integrally with eachother via integral molding, for example. Further, the first supportmember 26 and the second support member 28 may include a metallicmaterial. The first support member 26 and the second support member 28are formed integrally with each other via cutting or casting, forexample.

With the bicycle rear sprocket assembly 810, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Ninth Embodiment

A bicycle rear sprocket assembly 910 in accordance with a ninthembodiment will be described below referring to FIG. 12. The bicyclerear sprocket assembly 910 has the same configuration as the bicyclerear sprocket assembly 10 except for the first support member 26 and thesecond support member 28. Elements having substantially the samefunction as those in the above embodiments will be numbered the samehere, and will not be described again in detail here for the sake ofbrevity.

As seen in FIG. 12, in the bicycle rear sprocket assembly 910, the firstradially outer portion 30 of the first support member 26 is providedintegrally with the second radially outer portion 34 of the secondsupport member 28 as a single unitary member. Specifically, the firstradially outer parts 40 are respectively provided integrally with thesecond radially outer parts 44 as a single unitary member.

However, the first radially outer portion 30 is a separate member fromthe first arms 38. The first radially outer parts 40 respectively areseparate members from the first arms 38. The first radially outer parts40 are attached to the first arms 38 via one of adhesive, diffusionbonding, and caulking. For example, the first radially outer portion 30and the first arms 38 include a metallic material. The first radiallyouter portion 30 (the first radially outer parts 40) is attached to thefirst arms 38 via diffusion bonding.

With the bicycle rear sprocket assembly 910, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Tenth Embodiment

A bicycle rear sprocket assembly 1010 in accordance with a tenthembodiment will be described below referring to FIG. 13. The bicyclerear sprocket assembly 1010 has the same configuration as the bicyclerear sprocket assembly 10 except for the first support member 26 and thesecond support member 28. Elements having substantially the samefunction as those in the above embodiments will be numbered the samehere, and will not be described again in detail here for the sake ofbrevity.

As seen in FIG. 13, in the bicycle rear sprocket assembly 1010, thefirst radially outer portion 30 of the first support member 26 isprovided integrally with the second radially outer portion 34 of thesecond support member 28 as a single unitary member. Specifically, thefirst radially outer parts 40 are respectively provided integrally withthe second radially outer parts 44 as a single unitary member.

However, the second radially outer portion 34 is a separate member fromthe second arms 42. The second radially outer parts 44 respectively areseparate members from the second arms 42. The second radially outerparts 44 are attached to the second arms 42 via one of adhesive,diffusion bonding, and caulking. For example, the second radially outerportion 34 and the second arms 42 include a metallic material. Thesecond radially outer portion 34 (the second radially outer parts 44) isattached to the second arms 42 via diffusion bonding.

With the bicycle rear sprocket assembly 1010, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Eleventh Embodiment

A bicycle rear sprocket assembly 1110 in accordance with an eleventhembodiment will be described below referring to FIG. 14. The bicyclerear sprocket assembly 1110 has the same configuration as the bicyclerear sprocket assembly 10 except for the first support member 26 and thesecond support member 28. Elements having substantially the samefunction as those in the above embodiments will be numbered the samehere, and will not be described again in detail here for the sake ofbrevity.

As seen in FIG. 14, in the bicycle rear sprocket assembly 1110, thefirst radially outer portion 30 of the first support member 26 isprovided integrally with the second radially outer portion 34 of thesecond support member 28 as a single unitary member. Specifically, thefirst radially outer parts 40 are respectively provided integrally withthe second radially outer parts 44 as a single unitary member.

However, the first radially outer portion 30 is a separate member fromthe first arms 38. The first radially outer parts 40 respectively areseparate members from the first arms 38. The first radially outer parts40 are attached to the first arms 38 via one of adhesive, diffusionbonding, and caulking. For example, the first radially outer portion 30and the first arms 38 include a metallic material. The first radiallyouter portion 30 (the first radially outer parts 40) is attached to thefirst arms 38 via diffusion bonding.

Similarly, the second radially outer portion 34 is a separate memberfrom the second arms 42. The second radially outer parts 44 respectivelyare separate members from the second arms 42. The second radially outerparts 44 are attached to the second arms 42 via one of adhesive,diffusion bonding, and caulking. For example, the second radially outerportion 34 and the second arms 42 include a metallic material. Thesecond radially outer portion 34 (the second radially outer parts 44) isattached to the second arms 42 via diffusion bonding.

With the bicycle rear sprocket assembly 1110, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Twelfth Embodiment

A bicycle rear sprocket assembly 1210 in accordance with a twelfthembodiment will be described below referring to FIG. 15. The bicyclerear sprocket assembly 1210 has the same configuration as the bicyclerear sprocket assembly 10 except for the sprocket support member 12.Elements having substantially the same function as those in the aboveembodiments will be numbered the same here, and will not be describedagain in detail here for the sake of brevity.

As seen in FIG. 15, the bicycle rear sprocket assembly 1210 comprises asprocket support member 1212. The sprocket support member 1212 comprisesa first support member 1226 and a second support member 1228. At leastone of the first support member 1226 and the second support member 1228has an annular shape when viewed from in the axial direction D2. In thisembodiment, each of the first support member 1226 and the second supportmember 1228 has an annular shape when viewed from in the axial directionD2.

Specifically, the first support member 1226 includes a first radiallyouter portion 1230 and the first radially inner portion 32. The firstradially outer portion 1230 has substantially the same structure as thatof the first radially outer portion 30 in the first embodiment. Unlikethe first radially outer portion 30, however, the first radially outerportion 1230 has an annular shape.

The second support member 1228 includes a second radially outer portion1234 and the second radially inner portion 36. The second radially outerportion 1234 has substantially the same structure as that of the secondradially outer portion 34 in the first embodiment. Unlike the secondradially outer portion 34, however, the second radially outer portion1234 has an annular shape.

With the bicycle rear sprocket assembly 1210, it is possible to obtainthe same effects as those of the bicycle rear sprocket assembly 10 inaccordance with the first embodiment.

Thirteenth Embodiment

A bicycle rear sprocket 1310 in accordance with a thirteenth embodimentwill be described below referring to FIGS. 16 and 17. The bicycle rearsprocket 1310 has the same configuration as the bicycle rear sprocketassembly 10 except for the first sprocket 14, the second sprocket 16,the first sprocket attachment portion 50, and the second sprocketattachment portion 52. Elements having substantially the same functionas those in the above embodiments will be numbered the same here, andwill not be described again in detail here for the sake of brevity.

As seen in FIGS. 16 and 17, the bicycle rear sprocket 1310 comprises afirst attachment portion 1350 and a second attachment portion 1352instead of the first sprocket attachment portion 50 and the secondsprocket attachment portion 52. The first radially outer portion 30 ofthe first support member 26 is configured to be attached to the secondradially outer portion 34 of the second support member 28 via a bicyclesprocket 1316 positioned between the first attachment portion 1350 andthe second attachment portion 1352 in the axial direction D2. Thebicycle sprocket 1316 has substantially the same structure as that ofthe second sprocket 16 in the first embodiment. The bicycle sprocket1316 is attached to the first sprocket attachment portion 50 and thesecond sprocket attachment portion 52 via e.g. the rivets 58. Thebicycle sprocket 1316 may also be attached to the first sprocketattachment portion 50 and the second sprocket attachment portion 52 viaone of caulking, adhesive, integral molding, and diffusion bonding.

The first attachment portion 1350 is provided at the first radiallyouter portion 30 of the first support member 26. The second attachmentportion 1352 is provided at the second radially outer portion 34 of thesecond support member 28. The first radially outer portion 30 is spacedapart from the second radially outer portion 34 in the axial directionD2. The first attachment portion 1350 is spaced apart from the secondattachment portion 1352 in the axial direction D2. The first attachmentportion 1350 and the second attachment portion 1352 are provided betweenthe first radially outer portion 30 and the second radially outerportion 34 in the axial direction D2.

The first sprocket attachment portion 50 includes a first surface 1354.The second sprocket attachment portion 52 includes a second surface1356. The first surface 1354 faces the second surface 1356 in the axialdirection D2. The first surface 1354 is in contact with the bicyclesprocket 1316 in a state where the bicycle sprocket 1316 is attached tothe first attachment portion 1350. The second surface 1356 is in contactwith the bicycle sprocket 1316 in a state where the bicycle sprocket1316 is attached to the second attachment portion 1352.

With the bicycle rear sprocket 1310, the first support member 26 facesthe second support member 28 in the axial direction D2 to define theaxial gap G provided between the first support member 26 and the secondsupport member 28 in the axial direction D2. Accordingly, it is possibleto save weight of the bicycle rear sprocket 1310 with maintaining thedesired strength of the bicycle rear sprocket 1310.

It will be apparent to those skilled in the bicycle field from thepresent disclosure that the structures of the above embodiments can beat least partially combined with each other.

In the present application, the term “attached” or “attaching”, as usedherein, can encompass configurations in which an element is directlyattached to the other element by affixing the element directly to theother element; configurations in which the element is indirectlyattached to the other element via the intermediate member(s); andconfigurations in which one element is integral with the other element,i.e. one element is essentially part of the other element. This conceptalso applies to words of similar meaning, for example, “joined”,“connected”, “coupled”, “mounted”, “bonded”, “fixed” and theirderivatives.

The term “comprising” and its derivatives, as used herein, are intendedto be open ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. This concept also applies to words of similarmeaning, for example, the terms “have”, “include” and their derivatives.

The terms “member”, “section”, “portion”, “part”, “element”, “body” and“structure” when used in the singular can have the dual meaning of asingle part or a plurality of parts.

The ordinal numbers such as “first” and “second” recited in the presentapplication are merely identifiers, but do not have any other meanings,for example, a particular order and the like. Moreover, for example, theterm “first element” itself does not imply an existence of “secondelement”, and the term “second element” itself does not imply anexistence of “first element.”

The term “pair of”, as used herein, can encompass the configuration inwhich the pair of elements have different shapes or structures from eachother in addition to the configuration in which the pair of elementshave the same shapes or structures as each other.

Finally, terms of degree such as “substantially”, “about” and“approximately” as used herein mean a reasonable amount of deviation ofthe modified term such that the end result is not significantly changed.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A bicycle rear sprocket assembly comprising: asprocket support member rotatable about a rotational center axis, thesprocket support member having a first axial side and a second axialside opposite to the first axial side in an axial direction parallel tothe rotational center axis, the sprocket support member comprising: afirst support member including a first radially outer portion and afirst radially inner portion, the first support member at least partlyconstituting the first axial side; and a second support member includinga second radially outer portion and a second radially inner portion, thesecond support member at least partly constituting the second axialside, the first support member facing the second support member in theaxial direction to define an axial gap provided between the firstsupport member and the second support member in the axial direction, theaxial gap being an open space that extends from at least a portion ofthe first support member to at least a portion of the second supportmember in the axial direction; a first attachment portion provided atthe first radially outer portion of the first support member; a secondattachment portion provided at the second radially outer portion of thesecond support member; and the first radially outer portion of the firstsupport member being configured to be attached to the second radiallyouter portion of the second support member via a bicycle sprocketpositioned between the first attachment portion and the secondattachment portion in the axial direction.
 2. The bicycle rear sprocketassembly according to claim 1, wherein the first radially outer portionis spaced apart from the second radially outer portion in the axialdirection.
 3. The bicycle rear sprocket assembly according to claim 1,wherein the first attachment portion is spaced apart from the secondattachment portion in the axial direction.
 4. The bicycle rear sprocketassembly according to claim 1, wherein the first attachment portionincludes a first surface, the second attachment portion includes asecond surface, and the first surface faces the second surface in theaxial direction.
 5. The bicycle rear sprocket assembly according toclaim 4, wherein the first surface is in contact with the bicyclesprocket in a state where the bicycle sprocket is attached to the firstattachment portion, and the second surface is in contact with thebicycle sprocket in a state where the bicycle sprocket is attached tothe second attachment portion.
 6. The bicycle rear sprocket assemblyaccording to claim 1, further comprising: a hub engagement portion withwhich a bicycle hub assembly is to be engaged.
 7. The bicycle rearsprocket assembly according to claim 6, wherein the hub engagementportion is a separate member from at least one of the first radiallyinner portion of the first support member and the second radially innerportion of the second support member.
 8. The bicycle rear sprocketassembly according to claim 7, wherein the first radially inner portionis configured to be attached to the second radially inner portion viathe hub engagement portion.
 9. The bicycle rear sprocket assemblyaccording to claim 6, wherein the hub engagement portion is providedintegrally with at least one of the first radially inner portion of thefirst support member and the second radially inner portion of the secondsupport member as a single unitary member, and the hub engagementportion is directly attached to an other of the at least one of thefirst radially inner portion of the first support member and the secondradially inner portion of the second support member.
 10. A bicycle rearsprocket assembly comprising: a sprocket support member rotatable abouta rotational center axis, the sprocket support member having a firstaxial side and a second axial side opposite to the first axial side inan axial direction parallel to the rotational center axis, the sprocketsupport member comprising: a first support member including a firstradially outer portion and a first radially inner portion, the firstsupport member at least partly constituting the first axial side; and asecond support member including a second radially outer portion and asecond radially inner portion, the second support member at least partlyconstituting the second axial side, the first support member facing thesecond support member in the axial direction to define an axial gapprovided between the first support member and the second support memberin the axial direction; a first attachment portion provided at the firstradially outer portion of the first support member; a second attachmentportion provided at the second radially outer portion of the secondsupport member; and the first radially outer portion of the firstsupport member being configured to be attached to the second radiallyouter portion of the second support member via a bicycle sprocketpositioned between the first attachment portion and the secondattachment portion in the axial direction, wherein the first radiallyouter portion includes first radially outer parts, the second radiallyouter portion includes second radially outer parts, each of the firstradially outer parts includes a first attachment hole, each of thesecond radially outer parts includes a second attachment hole, and arivet extends through the first attachment hole and the secondattachment hole.
 11. A bicycle rear sprocket assembly comprising: asprocket support member rotatable about a rotational center axis, thesprocket support member having a first axial side and a second axialside opposite to the first axial side in an axial direction parallel tothe rotational center axis, the sprocket support member comprising: afirst support member including a first radially outer portion and afirst radially inner portion, the first support member at least partlyconstituting the first axial side; and a second support member includinga second radially outer portion and a second radially inner portion, thesecond support member at least partly constituting the second axialside, the first support member facing the second support member in theaxial direction to define an axial gap provided between the firstsupport member and the second support member in the axial direction; afirst attachment portion provided at the first radially outer portion ofthe first support member; a second attachment portion provided at thesecond radially outer portion of the second support member; and a hubengagement portion with which a bicycle hub assembly is to be engaged,wherein the first radially outer portion of the first support memberbeing configured to be attached to the second radially outer portion ofthe second support member via a bicycle sprocket positioned between thefirst attachment portion and the second attachment portion in the axialdirection, and the hub engagement portion is provided integrally with atleast one of the first radially inner portion of the first supportmember and the second radially inner portion of the second supportmember as a single unitary member.